ES2564554T3 - Procedure to treat water and treatment plant - Google Patents

Abstract

Procedure for treating water (4) in a treatment plant (1), in particular wastewater in a purification treatment plant, which has a reaction chamber (2) in which a biodegradable material (5) present in the water ( 4) is at least partially biodegraded by the microorganisms (17) and has a separation chamber (3) in which the biodegradable material (5) and the microorganisms (17) are at least partially separated from the water (4), a water stream (6) containing the microorganisms (17) and the biodegradable material (5) that flows from the reaction chamber (2) to the separation chamber (3), characterized in that a return stream (7) containing the biodegradable material (5) and the microorganisms (17) flows from the separation chamber (3) to the reaction chamber (2) and the return stream (7) is subjected to a treatment in which, a portion of the microorganisms (17) located in the return pipe (7) is destroyed by a biocide, in particular by ozone, forming dead microorganisms, presetting the intensity of the treatment to preset at least one feed rate of the group: -a first feed rate of the living microorganisms recirculated from the separation chamber (3) to the reaction chamber ( 2), -a second feed rate of the dead microorganisms (17) recirculated from the separation chamber (3) to the reaction chamber (2), -a third feed rate of the biodegradable material (5) recirculated from the chamber separation (3) to the reaction chamber (2), at least one feed rate of the group consisting of the first feed rate and the second feed rate preset by a portion of the microorganisms (17) located in the stream return (7) that is destroyed.

Description

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DESCRIPTION

Procedure to treat water and treatment plant

The invention relates to a process for treating water in a treatment plant, in particular wastewater in a treatment plant, and a treatment plant for treating water.

The use of biological filters, fixed bed systems and membrane biological procedures as a supplement for conventional plant designs in the purification of industrial or domestic wastewater is known. Biological procedures are affected in this case by introducing substances, for example, oxygen or carbon dioxide, into the wastewater.

Thus, the oxygen content required for biological activity can be adjusted by adding pure oxygen and the pH required for biological activity by adding carbon dioxide. An introduction of ozone in combination with stages of aerobic biological treatment, is done to oxidize or decompose poorly degradable substances. The ozone treatment is generally carried out downstream of a biological purification. In partial oxidations, ozone adheres to the poorly degradable constituents that remain in the effluent and thus makes them susceptible to subsequent economic biological purification.

In addition, the method by which a reaction tank and a decanting tank in treatment of treatment plants is provided is known, in which case the organically degradable materials are degraded by microorganisms in the settling tank and the remaining organic material in the tank. Decantation separates from water. In this case, the material from the separation tank separated from the water is partially recirculated back to the reaction tank.

A disadvantage of this treatment is that the sludge decanted in the separation tank cannot be completely recirculated to the reaction tank, since the reaction tank is biologically overloaded as a result of the addition of excessive amounts of concentrated sludge, with which can happen a transition to anoxia and with which the microorganisms that live in the reaction tank can die.

For this reason, it has been necessary to separately dispose of 10 to 20% of the sewage sludge that forms in the settling tank, which is often considered as special waste. Disposal of this sewage sludge produces high costs that represent up to 30% of the operational costs of a treatment plant.

Secondly, the use of ozone to treat recirculated water is known, for example, in cooling systems of electric stations, in order to prevent the formation of silt in water as a result of biological activity. Ozone is used herein as a biocide, which does not contribute to salt accumulation and effectively suppresses biological activity even at relatively low doses.

Patent documents EP835845, DE19942184, US4370235, WO99 / 41205 and EP881195 describe methods for treating water in a treatment silver having a reaction chamber, then a separation chamber and a return current from the separation chamber to the chamber of reaction, said return current being subjected to an ozone treatment.

It is therefore an object of the present invention, to provide a process for treating water and a treatment plant with which dirty wastewater can be treated in an economical manner, generating organic sewage sludge in much lower amounts.

This object is achieved in accordance with the invention, by a method for treating water with the characteristics according to claim 1 and by a treatment plant for treating water with the characteristics according to claim 12.

Other embodiments and advantageous developments, each of which can be used individually or can be combined with each other as desired, are the object treated in the respective dependent claims.

The process of the invention for treating water in a treatment plant, in particular wastewater, in a treatment plant, which has a reaction chamber in which a biodegradable material present in the water, is at least partially biodegraded by microorganisms and which has a separation chamber in which the biodegradable material and the microorganisms are separated at least partially from the water, a stream of water containing microorganisms and biodegradable material flowing from the reaction chamber to the separation chamber, is characterized in that a return current containing biodegradable material and a portion of the microorganisms flows from the separation chamber to the reaction chamber, and the return current is subjected to a treatment whose intensity is previously set.

The function of the reaction chamber is to degrade the biodegradable material present in the water by microorganisms. It is this procedure, the microorganisms fed on the biodegradable material, are

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multiply and break down or oxidize hydrocarbon compounds of the material with the release of carbon dioxide, water and nitrogen.

It is advantageous if the water containing biodegradable material and microorganisms is kept in constant agitation in the reaction chamber, to achieve constant mixing. This agitation of water ensures a particularly good biological activity of microorganisms.

The function of the separation chamber is to separate the water from the organically degradable material and the microorganisms. This separation can be achieved, for example, by simple decantation of the microorganisms or the material in a decantation tank. Water essentially free of microorganisms and material can be removed from the separation chamber and, if appropriate, is subjected to a subsequent purification step.

Separated microorganisms and biodegradable material are recirculated back to the reaction chamber. In this case, the dead material and microorganisms serve as a nutrient for the microorganisms that live in the reaction chamber. Live microorganisms removed from the separation chamber and added to the reaction chamber contribute to the biological activity in the reaction chamber. However, attention should be paid to the fact that the supply of superabundant or very scarce food in the reaction chamber and an excessive or insufficient population of microorganisms causes interference in the biological procedure in the reaction tank.

To avoid the transition to the anoxia of the water in the reaction chamber, that is, what is called population catastrophe, according to the invention, the return current containing biodegradable material and a portion of the microorganisms is subjected to a treatment whose intensity is set previously. In this treatment, at least one factor of three factors is taken into account, that is, the feed rate of the recirculated organic material, the feed rate of the live microorganisms and / or the feed rate of the dead microorganisms. The feed rate is defined as the amount that flows in the reaction chamber (in units, for example, particles, liters or kilos per time period).

Experience shows, for example, that an excessively high feed rate of living microorganisms causes a sharp rise in the population in the reaction tank. The increase continues until the entire food supply is depleted. The population of microorganisms then collapses. Although, as a result, the organic material is removed from the water, the population of microorganisms is so low that, in the case of providing a new supply of wastewater containing organic material to the reaction tank, only a slow degradation of the material will occur. organic due to the low population.

If, on the other hand, the feeding rate of live microorganisms is very low, and more live microorganisms are removed from the reaction chamber than those generated in the reaction chamber, the population of microorganisms in the reaction chamber decreases from such that, again, a flow-type addition of large amounts of organic material cannot be processed quickly.

In the case of an excessive feed rate of organically degradable material, it produces in the short term an excess of nutrients followed by an excessively high population of microorganisms. Subsequently, again, a population catastrophe can be expected, that is, an abrupt collapse of the population of microorganisms.

If, on the other hand, an insufficient amount of organic material is fed to the reaction tank, the population of microorganisms can decrease to a critical point due to a deficiency of nutrients, if there is not enough organic material in the wastewater.

Dead or destroyed microorganisms have also proven to be good nutrients for living microorganisms. An excessively high feeding of dead microorganisms can also produce an excessive population increase and subsequent population catastrophe.

In general, when treating the return current influencing at least one feed rate of the feed rate of live microorganisms, feed rate of dead microorganisms and feed rate of organically degradable material, intense fluctuations are avoided in the purification capacity of the water treatment plant. By presetting the intensity and type of treatment, the biological activity in the reaction tank can be influenced. In particular, population catastrophes or excessive population fluctuations can be avoided in this way.

In an embodiment of the process of the invention, the treatment preset a first feed rate of the microorganisms fed to the reaction chamber. If the biological activity in the reaction tank is in the subcritical range, that is, the population of microorganisms is less than the supply of nutrients, by presetting the first feeding rate directly influences the population growth.

In another embodiment of the process of the invention, the treatment preset a second feed rate of the dead microorganisms recirculated from the separation chamber to the reaction chamber.

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As a result of the recirculation of dead microorganisms, a growth of the population of microorganisms in the reaction chamber is particularly reinforced, since dead microorganisms are particularly good nutrients for living microorganisms. Feeding can stimulate growth, in particular, in the case of small population sizes.

In another embodiment of the process of the invention, a third feed rate of the material recirculated to the reaction chamber is preset. The supply of nutrients in the reaction space is determined jointly through the third feed rate. If, for example, a wastewater rich in organic material is absent for a short time, a feed of appropriate dimensions of organic material from the separation chamber can compensate for the nutrient deficit in the reaction chamber. As a result, a population catastrophe is avoided in the reaction chamber, and by which it is possible to standardize the biological activity over time and level out the population fluctuations.

In order to preset at least one feed rate of the first feed rate and the second feed rate of the group, a portion of the microorganisms present in the return current is advantageously destroyed. By destroying living microorganisms, the relationship of living microorganisms to dead microorganisms can be influenced. Depending on the supply of nutrients and size of the population of microorganisms in the reaction tank, a certain ratio of living microorganisms to dead microorganisms in the reaction tank produces an increase or decrease in the population.

For example, a low ratio, that is, a feed of many dead microorganisms to the reaction chamber with a biological activity in the critical range, that is, when the ratio of the population to food supply in the reaction tank is just in balance, it produces an increase in the population. Although a high ratio, that is, a diet of many microorganisms but few dead microorganisms, increases the population in the short-term reaction chamber, the population then collapses due to the low supply of nutrients.

Advantageously, a portion of the microorganisms present in the return stream is destroyed by a biocide, in particular by ozone. The advantage of ozone is that ozone, after fluoride, is the strongest oxidizing agent, but it reacts to form comparatively non-problematic oxidation products and oxygen. Oxygen is required anyway in the reaction in the reaction chamber. In addition, there is no accumulation of salts in the treated waters as a result of oxidation with ozone.

Although ozone cannot be stored, it can be produced in situ from oxygen in ozone generators. For industrial applications, ozone concentrations of 10 to 14% by weight can be achieved with an energy consumption of less than 10 kWh / kg of ozone.

Advantageously, the removal rate of the microorganisms removed from the reaction chamber and fed to the separation chamber is greater on average in time than the reproduction rate of the microorganisms in the reaction chamber. As a result, more microorganisms are removed from the reaction chamber than those generated as microorganisms by cell division. By an appropriate addition of microorganisms in the return current, that is, by means of an appropriate first feed rate, the population in the reaction chamber can be maintained at a certain level in a controlled manner. A withdrawal of microorganisms sufficiently high avoids population uncontrollable population fluctuations in the reaction chamber in advance.

Advantageously, at least one feed rate of the first feed rate, second feed rate and third feed rate of the group is controlled, depending on the concentration of the microorganisms located in the reaction chamber. Through control, the population in the reaction chamber can be controlled.

The control parameter used can be either the first feed rate, that is, the amount of live microorganisms that are incorporated per unit of time into the reaction chamber, or the amount of nutrients in the form of dead microorganisms, i.e. , as a second feed rate, or in the form of biodegradable material, that is, as a third feed rate. With particular preference, a plurality of feed rates are preset and used for control based on the size of the population of microorganisms in the reaction tank and the supply of nutrients in the reaction tank.

It is advantageous that the concentration of ozone in the return stream at a feeding point is between 20 and 60 g / l, in particular between 30 and 50 g / l, preferably between 40 and 44 g / l. These values refer in particular to return currents in sewage treatment plants that have the usual material concentrations for sewage treatment plants. Depending on the efficiency of the separation chamber and the concentration of material achieved, the ozone concentration will be correspondingly higher or lower.

Experience has shown that, depending on the concentration of the organically degradable material in the water, between 5 and 30%, in particular between 10 and 20%, of the microorganisms removed from the separation chamber and fed to the chamber must be destroyed of reaction. With this relationship a particularly stable population is achieved in the reaction tank. More advantageously, the microorganisms predominantly

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Low biological activity are destroyed by the biocide and microorganisms with a strong biological activity are left alive.

The volumetric flow rate of the water to be treated fed to the reaction chamber is of such magnitude that the water in the reaction chamber is exchanged in the course of 2 to 6 days, in particular in the course of 3 to 5 days. As a result of these flows, a sufficiently high flow is achieved with a sufficiently good clarification action. The usual capacity of the reaction chamber is at least 3,000 m3, in particular at least 5,000 m3, preferably at least 7,000 m3.

To increase the biological activity, the organic structures present in the return current are mechanically or chemically fragmented. A mechanical fragmentation is performed that alters the organic structures. The addition of oxidizing agents chemically breaks down the organic structures and weakens the cell walls. Fragmentation enhances the biological activity in the reaction tank.

To further enhance the biological activity, the return current is conducted in an open circuit. The open circuit increases residence time and destroys cellular structures. Open, in this context, means that only a portion of the water containing organic material and microorganisms is circulated. The open circuit is achieved through an additional pipe, which is connected at both ends to a return pipe for the return current. In this case, it is preferred that the size of the circuit be at least twice, in particular at least three times, preferably four times greater than the return current. The circuit increases the residence time of the return current in the return pipe and the group structures are fragmented. As a result, it is possible to dissolve the total amount of oxidizing agent in the medium.

Advantageously, in the reaction tank, the content of organic material in the water is maintained at 3 to 5 g / l, in particular it is controlled at 3 to 5 g / l. This concentration of organic material achieves a particularly effective and stable biological activity in the reaction tank.

In the separation chamber, advantageously, the content of organic material in the water is controlled at 6 to 20 g / l averaged in space. It is advantageous that the ozone concentration is such as to keep vital microorganisms alive in the return stream and that weak microorganisms die.

In a special embodiment of the invention, the separation chamber used is a decantation tank. Also, it is convenient to use the membrane systems to separate the mud from the water in the separation chamber. Using a settling tank, the organic material and microorganisms are separated from the water in a simple and economical way.

The treatment plant of the invention for treating water, in particular a wastewater treatment plant, which has a reaction chamber for biodegradation of biodegradable material by microorganisms and a separation chamber for at least partial separation of the biodegradable material and water microorganisms, the reaction chamber and the separation chamber that is connected through a feed pipe for water containing microorganisms and biodegradable material, and a return pipe for degradable material and microorganisms, is characterized by having a treatment device for treating a return current from the separation chamber to the reaction chamber.

Through a feed pipe for water containing microorganisms and biodegradable material, starting from the reaction chamber to the separation chamber, water and microorganisms and organically degradable material are removed from the reaction chamber and fed to the separation chamber . The return pipe removes water enriched with microorganisms and biodegradable material from the separation chamber, and feeds this to the reaction chamber. The treatment device treats the return current and thus influences the growth or size of the population of microorganisms in the reaction chamber.

In an embodiment of the invention, the treatment device has a measuring device to preset a first feed rate of the microorganisms removed from the separation chamber and fed to the reaction chamber. The measuring device determines this way! The first feed rate. The mode of operation of the measuring devices can be either by physical separation of the microorganisms present in the return current, or by chemical destruction of the microorganisms, or by biological inoculation with suitable strains of microorganisms.

In another embodiment of the invention, the treatment device has a measuring device for presetting a second feed rate of dead microorganisms fed to the reaction chamber. Depending on the measurement devices to preset the first feed rate, the second feed rate can be preset in various ways.

In another embodiment of the invention, the treatment device has a measuring device for presetting a third feed rate of the material removed from the separation chamber and fed to the reaction chamber. Through this measuring device, the nutrient feed to the reaction chamber was determined.

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Advantageously, the measuring device comprises a feeding point for a biocide in the return pipe. A suitable biocide is, for example, ozone. Alternatively, the biocide used is another bacteriological strain that affects the microorganisms in the reaction tank.

Advantageously, the feeding point comprises a vacuum pump. Using the vacuum pump, gases can be introduced in a simple way, for example, ozone or carbon dioxide, into the return stream.

In an advantageous embodiment of the treatment plant of the invention, the measuring device comprises a sensor to determine at least one concentration from the group concentration of living microorganisms located in the reaction chamber, the concentration of dead microorganisms located in the reaction chamber and the concentration of organically degradable material located in the reaction chamber. Using the sensor and the measuring device, the population of microorganisms in the reaction chamber is controlled. The sensor helps to monitor the biological activity in the reaction chamber.

In a special embodiment of the invention, at least one additional pipe is connected through both of its ends to the return pipe. The additional pipe generates an open circuit in the return pipe through which the group structures in the return current can be destroyed. A pump in the additional pipe helps maintain the circuit.

Advantageously, the separation chamber is a deposit of decantation. It is advantageous that the separation chamber has a membrane system for separating mud and water.

To fragment the group structures and enhance the biological activity in the reaction chamber, a mechanical fragmenter is provided in the return pipe. By fragmenting the biodegradable material, a larger specific surface is achieved and results in a faster degradation of the biological material.

The capacity of the reaction chamber is advantageously at least 1,000 m3, in particular at least 6,000 m3.

Next, other advantages and embodiments will be explained with reference to the drawings.

The figure diagrammatically shows a treatment plant 1, for treating water 4, which has a reaction chamber 2 and a separation chamber 3. The water to be treated is fed through a waste water inlet 19, to the reaction chamber 2. In the reaction chamber 2, the water 4, which contains the biodegradable material 5, is mixed together with the microorganisms 17, which feed on the biodegradable material 5 and decompose it.

The reaction chamber 2, is connected through a feed pipe 9, to the separation chamber 3. A portion of water 4, which contains biodegradable material 5 and microorganisms 17, is fed through a feed pipe 9, as the water stream 6, to the separation chamber 3. In the separation chamber 3, the water 4, is separated from the organic material 5 and the microorganisms 17. The material 5 and the microorganisms 17, settle as sludge of depuration at the bottom of the separation chamber 13. Thus, the water 4 essentially free of the material 5 and microorganisms 17 is removed through a clean water outlet 20.

The material 5, which sits in the separation chamber 3, is recirculated as a return current 7, together with the remaining water and the microorganisms 17, in a return pipe 10, after a treatment by a treatment device 22 , to the reaction chamber 2. Thus, the biodegradable material 5 and the microorganisms 17 are fragmented by means of a fragmenter 16 and then the return stream 7 with ozone is incorporated into a feeding point 12.

In the return pipe 10, a pump 14 is provided to transport the return current 7. For further fragmentation of the organic material 5, a mixing pipe 23 is present, in which the water 4 is circulated, which contains material organically degradable 5 and microorganisms 17. This additional mixing leads to more fragmentation of the group structures.

The return current 7 is incorporated into a supply point 12 with ozone, the addition of which is determined by a control unit 15, depending on the density of the microorganisms 17, in the reaction chamber 2, measured by a sensor 18 The sensor 18, the control unit 15 and the feeding point 12, together form a measuring device 11, whereby a first feed rate of live microorganisms that are incorporated into the reaction tank 2 can be preset. Proper presetting of the intensity of treatment of the return current 7, means that a majority of the sludge that is formed in the separation space 3, is eliminated by the microorganisms 17, in the form of biodegradable material 5, or in of microorganisms 17. The operational costs of a sewage treatment plant are lower, because there is a lower amount of special waste to be disposed of.

An additional pipe 13, which contains a pump 24, ensures a subsequent circuit 8, which achieves a particularly good mixing of the water 4, with ozone and a fragmentation of the remaining cellular structures. By means of the residual sludge outlet 21, the residual sludge is removed from the separation chamber 3 and the return pipe 10.

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The return pipe 10, for the return current 7; the residual sludge outlet 21; the pump 14; the fragmenter 16; mixing pipe 23; the additional pipe 13, for the open circuit 8, which contains the pump 24; The measuring device 11, comprising the sensor 18, the control unit 15 and the feeding point 12, together form the treatment device 22.

The open or closed loop control of the interaction of the individual components determines the intensity of the treatment of the return current 7. A balanced population is achieved in the reaction chamber 2, which is uniform in time and not subject to large fluctuations

The process of the invention for treating water 4, in a treatment plant 1, in particular wastewater in a treatment plant, which has a reaction chamber 2, in which a biodegradable material present in the water 4, is at less partially biodegraded by microorganisms 17 and a separation chamber 3, in which the biodegradable material 5 and the microorganisms 17, are at least partially separated from the water 4, a stream of water 6 containing microorganisms 17 and biodegradable material 5, which flows from the reaction chamber 2, to the separation chamber 3, is characterized in that a return current 7, which contains biodegradable material 5 and a portion of the microorganisms 17, flows from the separation chamber 3, to the reaction chamber 2 and the return current 7, is subjected to a treatment whose intensity is preset.

The process of the invention and the treatment plant of the invention for carrying out the process of the invention, are distinguished by a decrease in the sludge produced and provide a particularly economical method for treating water.

List of designations

1 treatment plant

2 Reaction chamber

3 Separation chamber

4 Water

5 Material

6 Water stream

7 Return current

8 Circuit

9 Feed pipe

10 Return pipe

11 Measuring means

12 feeding point

13 Additional pipe

14 Bomb

15 Control Unit

16 Fragmenter

17 Microorganisms

18 Sensor

19 Wastewater inlet

20 Clean water outlet

21 Waste sludge outlet

22 Treatment device

23 Mixing Pipe

24 Bomb

Claims (19)

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Procedure for treating water (4) in a treatment plant (1), in particular wastewater in a treatment plant, which has a reaction chamber (2) in which a biodegradable material (5) is present in the Water (4) is at least partially biodegraded by microorganisms (17) and has a separation chamber (3) in which the biodegradable material (5) and microorganisms (17) are at least partially separated from water (4) , a stream of water (6) containing the microorganisms (17) and the biodegradable material (5) flowing from the reaction chamber (2) to the separation chamber (3), characterized in that a return current (7) containing the biodegradable material (5) and The microorganisms (17) flows from the separation chamber (3) to the reaction chamber (2) and the return current (7) is subjected to a treatment in which a portion of the microorganisms (17) located in the return pipe (7) is destroyed by a biocide, in particular by ozone, forming dead microorganisms, presetting the intensity of the treatment to preset at least one feed rate of the group: -a first feed rate of living microorganisms recirculated from the separation chamber (3) to the reaction chamber (2), -a second feed rate of the microorganisms (17) dead recirculated from the separation chamber (3) to the reaction chamber (2), - a third feed rate of the biodegradable material (5) recirculated from the separation chamber (3) to the reaction chamber (2), at least one feed rate of the group consisting of the first feed rate and the second feed rate preset by a portion of the microorganisms (17) located in the return current (7) that is destroyed. 2. Method according to claim 1, characterized in that at least one feed rate of the group consisting of the first feed rate, the second feed rate and the third feed rate, is controlled according to the concentration of the live microorganisms (17) located in the reaction chamber (2). Method according to one of the preceding claims, characterized in that the concentration of ozone in the return stream (7) at a feeding point (12) is between 20 and 60 g / l, in particular between 30 and 50 g / l, preferably between 40 and 44 g / l. Method according to one of the preceding claims, characterized in that between 5 and 30%, in particular between 10 and 20%, of the microorganisms (17) removed from the separation chamber (3) and fed to the reaction chamber (2) are destroyed. 5. Method according to one of the preceding claims, characterized in that a volumetric flow rate of the water (4) to be treated is fed to the reaction chamber (2) in such a magnitude that the water (4) in the reaction chamber (2) is exchanged in the course of 2 to 6 days, in particular in the course of 3 to 5 days. Method according to one of the preceding claims, characterized in that the return current is such that the water (4) in the reaction chamber (2) is exchanged in the course of 0.5 to 4 days, in particular in the course of 1 to 3 days. Method according to one of the preceding claims, characterized in that the group and cell structures present in the return current (7) are mechanically or chemically fragmented. Method according to one of the preceding claims, characterized in that the return current (7) is conducted to an open circuit (8) in which only a portion of the water containing the biodegradable material and the microorganisms is circulated, to increase residence time and destroy cell structures. 9. Method according to one of the preceding claims, characterized in that in the reaction tank, the content of dry organic matter in the water (4) is controlled at 3 to 5 g / l. Method according to one of the preceding claims, characterized in that in the separation chamber (3), the content of biodegradable material (5) in the water (4) is controlled at 6 to 20 g / l averaged in space. . Method according to one of the preceding claims, characterized in that the separation chamber (3) used is a settling tank and / or in the separation chamber (3) a membrane system is used to separate the sludge and the Water. 5 10 fifteen twenty 25 30 35 40 12. Treatment plant (1) to treat water (4), in particular a sewage treatment plant for wastewater, which has -a reaction chamber (2) for biodegradation of biodegradable material (5) by microorganisms (17), and -a separation chamber (3) for at least partial separation of the biodegradable material (5) and the microorganisms (17) from the water (4), -the reaction chamber (2) and the separation chamber (3) that are connected through a feed pipe (9) for the water (4) containing the microorganisms (17) and biodegradable material (5), and -a return pipe (10) for the biodegradable material (5) and the microorganisms (17), characterized by - a treatment device (22) for treating a return current (7) from the separation chamber (3) to the reaction chamber (2); the treatment device (22) having a measuring device (11) to preset at least one of the following speeds: -a first feed rate of living microorganisms recirculated from the separation chamber (3) to the reaction chamber (2), -a second feed rate of dead microorganisms (17) recirculated from the separation chamber (3) to the reaction chamber (2), - a third feed rate of the biodegradable material (5) recirculated from the separation chamber (3) to the reaction chamber (2), the measuring device (11) comprising a feeding point (12) for the biocide, in particular ozone, in the return pipe (10,7). 13. Treatment plant (1) according to claim 12, characterized in that the feed point (12) comprises a vacuum pump. 14. Treatment plant (1) according to claims 12 or 13, characterized in that the measuring device (11) comprises a sensor (18) for determining at least one concentration of the group consisting of the concentration of living microorganisms ( 17) present in the reaction chamber (2), the concentration of dead microorganisms present in the reaction chamber (2) and the concentration of organically biodegradable material (5) present in the reaction chamber (2). 15. Treatment plant (1) according to claims 12 to 14, characterized in that at least one additional pipe (13) is connected through both of its ends to the return pipe (10). 16. Treatment plant (1) according to claim 15, characterized in that a pump (14) for generating a circuit (12) is present in the additional pipe (13). 17. Treatment plant (1) according to one of claims 12 to 16, characterized in that the separation chamber (3) is a decantation tank and / or the separation chamber (3) has a membrane system to separate Water and mud. 18. Treatment plant (1) according to one of claims 12 to 17, characterized in that a mechanical fragmenter (16) is provided in the return pipe (10). 19. Treatment plant (1) according to one of claims 12 to 18, characterized in that the capacity of the reaction chamber (2) is at least 1,000 m3, in particular at least 6,000 m3.